1. Field of the Invention
The present invention relates to a wrist mechanism attached to, for example, a distal end of an arm of an industrial robot.
2. Prior Art Statement
Industrial robots are usually provided with bendable wrist mechanisms. Japanese Utility Model (18-month) Publication 56-160790 discloses a representative wrist mechanism as shown in FIGS. 1 and 2, in which a link mechanism 3 is jointed by means of a universal joint to a base member 1 attached to a robot body, the link mechanism 3 including one or more links 6 jointed by means of universal joints. Connecting rods 2 are attached to links 6 by means of universal joints mounted to the opposite ends thereof. The distal link 6 is provided with an operating tool 4. This wrist mechanism is, as shown in FIG. 2, bent by actuating a cylinder 5 of which rod is connected to the proximal link 6.
This prior art wrist mechanism is disadvantageous in that it is rather complicated in structure and large in size in spite of small rigidity since a large number of links and universal joints are used, and in that it is rather small in working area. Furthermore, the wrist mechanism necessitates a dust cover for preventing dust from entering into the connecting points.